<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>层次选择器</title>
    <link rel="stylesheet" href="../css.css">
</head>
<body>

<div class="container">

    <div class="row">row-1</div>
    <div class="">
         <div class="col-2">
             <div class="inner  row">inner-row-1</div>
             <div class="inner row">inner-row-2</div>
             <div class="inner row">inner-row-3</div>
         </div>
    </div>
    <div class="">row-3</div>

</div>

</body>
</html>